The harp and socket should never be visible below the lamp shade. We mount shades such that at eye level, the bottom of the shade should cover the base of the socket and be mounted at mid point of the neck. The shade should be long enough to cover the socket when viewed at eye level.
If shade looks good, but vertical positioning is the only problem, the shade can be raised or lowered by using a different size harp or a shade riser. A taller harp will allow the shade to be mounted higher up, or indeed lower down, so that you can center it and cover the hardware. A shade riser is a small adapter which extends the threaded pole on top of the harp fitter.
The lower the lamp is displayed, the higher the shade should sit. The higher the lamp is displayed, the lower the shade should sit.
HIDE THE HARDWARE
The shade should be long enough to cover the socket.